Regulating transformer



F. RAMPACHER 2,186, 07

REGULATING TRANSFORMER Filed Sept. 3,1937

3 5w/ cu cmvrAc-r nsnnses I5 um! novesmumwmsm WITNESSES: INVENTORPatented Jan. 9, i940 UNITED STATES PATENT OFFICE 2,186,207 REGULATINGTRANSFORMER Application September 3, 1937, Serial No. 162,298

In Germany March 30, 1937 7 Claims.

My invention relates to regulating transformers such as may be employedto vary the voltage supplied to a motor or other electrical apparatus.

An object of my invention is the provision of i a regulating transformerhavingmeans for varying the secondary or output voltage without thenecessity of employing switching devices on the low-voltage oroutputside of the transformer where high current carrying capacity isrequired.

Another object of my invention is the provision of a multiple-legregulating transformer for supplying a variable voltage secondary loadin which the voltage output from one portion is available to supplycurrent to load devices requiring a constant voltage supply.

Other objects and. advantages of my invention will appear from thefollowing description of preferred embodiments thereof, reference beinghad to theaccompanying drawing in which:

Figure 1 is a diagrammatic view of one embodiment of the invention; and

Figs. 2 and 3 illustrate modified arrangements of the tap changingswitches and circuits.

Referring to Fig. 1, a regulating transformer 2 5 is illustrated forsupplying energy to a motor I, such, for example, as the motor of anelectric locomotive, the transformer comprising a core structure 3provided with three winding legs about which are wound primary windings4, 5

l and 6, and secondary windings I, 6 and 9, re-

spectively. The two primary windings 5 and 6 are regulated windingsprovided with tap changing switches for changing the efiective number ofturns. The primary windings are supplied 5 with energy from an overheadconductor I9 through a-circuit that extends from the conductor Ill,through a trolley II, winding 4, conductor I 2, a portion of the winding5 depending upon the position of a movable switch contact II,

conductor I4, a portion of the winding 6 depending upon the pos tion ofa movable switch contact I5, conductor IE to ground at IT. This circuitconnects the primary windings I, 5 and 6 in series, the windings 5 and 6being so arranged I that their magnetizing efl'ect is cumulative withthat of" the unregulated winding 4. The tap changing switches I3 and I5are moved together, step by step, upwardlyand downwardly to engagecorresponding fixed contact members associated so that the sum of thenumber of turns in the winding 5 and in the winding 6 that. areconnected inseries with the unregulated winding 4' is at all timesapproximately constant.

The secondary windings 1, 9 and 9 are also connected-in series by acircuit extending from the grounded conductor I6 through the winding 1,conductor I9, winding 9, conductor I9, winding 3, through the motor I toground. The circuit connections are so arranged that the magnetizing e1-fect of the windings 1 and 9 are cumulative and are opposed by themagnetizing effect of the winding 8.

The outer primary windings 5 and 6 are provided with spaced tapconnections leading to m stationary switch contact members, thoseassociated with the winding 5 being connected to K members a, b, c, d,e, f, g, h and i, and those associated with the winding 6 beingconnected to members m, n, 0, p, q, r, s, t and u, respectively. The tapchanging mechanism actuates the movable sw'tch contact members I3 and I5upwardly or downwardly in synchronism so that the two movable contactmembers are always on corresponding taps of the two windings. In theillustrated position of the contact members I3 and I5, which are inengagement with the lower fixed contact members i and u, respectively,the primary series circuit includes the entire winding 5 and excludesthe entire winding 6 corresponding to a minimum secondary output voltageapplied to the motor I. If the contact members I3 and I5 are in theirextreme upper positions in engage- 'ment with the fixed contact membersa and m,

respectively, the series circuit will exclude substantially all of thewinding 5 and include all of the winding 6 to effect a maximum voltageoutput applied to the motor I. For intermediate positions of the contactmembers I3 and I5, corresponding portions of the windings 5 and 6 willbe included in the primary winding circuit.

The transformer may be so designed that the number of turns in each ofthe three primary windings 4, 5 and 6 are alike, and the number of turnsin each of the secondary transformer windings 1, 8 and 9 are alike, inwhich case half of the potential between the conductor I0 and ground isapplied to the unregulated primary winding 4, the rema ning half beingapplied across varying portions of the regulated windings 5 and 6depending upon the positions of the tap changing switches I3 and I5.

In such a design, with the tap changing switches I3 and I5 in theirlower or illustrated positions, the output voltage will besubstantiallyzero, since the voltages across the primary windings 5 and are equal,and the voltages across the. corresponding secondary windings 8 and Iare equal and opposite, and the voltage across the winding 9 associatedon the same winding leg as the primary winding 6 is substantially zero.If

the switch contact members 18 and I5 are raised tact members are movedindependently of one to engage the fixed contact members e and q,respectively, half the number of turns of each primary winding 5 and 8is included in the series connectin and the voltage output fromeach oithe windings 8 and 9 will be half the voltage output of thewinding 1,but since they are connected in opposition, will cancel out and causethe secondary winding output voltage to correspond to the voltage of thesecondary winding 1. If the contact members 13 and 15 are raised totheir upper positions in engagement with the fixed contact members a andm, respectively, substantially, the entire primary winding 5 is excludedfrom the primary series circuit, and the entire winding 6 is included sothat the output voltage of the secondary winding 8 is reducedsubstantially to zero, and the output voltage of the secondary winding 9is equal to the output voltage of the secondary winding 1 and in thesame vector relation, so that when these two voltages are added, thesecondary outputvoltage applied to the motor I is substantially twicethe voltage across the secondary winding 1. For intermediate positionsofthe tap changing switch contact members 13 and l5,.corresponding ratiosin the output voltages of the windings 8 and 9 are developed and soadded vectorially as to control the voltage applied to the motor I.between the maximum "and minimum above indicated. 4 It will be notedthat regardless of the positions of the tap changing switches i3 and 15,the voltage applied aci'oss the unregulatedprimary winding 4 is always adefinite proportion (in the assumed design, onehalf) the total voltagebetween the overhead conductor I0 and ground, and the output voltagefrom the secondary winding 1 is, therefore, a constant value regardlessof the positions of the tap changing switches 13' and i5 and of theoutput voltage of the three series connected'secondary windings.-Consequently, the secondary winding I may be employed to supply energyto electrical apparatus requiring a constant potential supply source,such as the lamps indicated by the numeral 22, L

A high resistance resistor 28 may be connected: between the terminal ofthe primary winding 4 that is not connected to the trolley wire andground, that is, between conductor 12 and ground, to prevent chargingthe low voltage end of the primary winding to a high potential uponfailure of a tap changing switch to maintain the intended seriesconnection, A high .resistance resistor 24 may also be providedconnected between the lower illustrated terminal of the primary winding5 and the upper illustrated terminal of the primary winding 8 to effectthe same purpose, or both resistors 23 and 24 'may be provided.

If it is desired to provide a larger number of tap changing steps, anarrangement such as that diagrammatically illustrated in Figs. 2 and 3may be provided, wherein movable switch contact members 24' and 25replace the contact member l8 of Fig. 1 and movable switch contactmembers 21 and 28 replace the movable contact member 15. In Fig. 2, aprotective auto-transformer 28 is connected between the contact members24 and 25, and a like protectiveauto-transformer is connected betweenthe contact members 21 and 28, the mid-points of which are oined by theconductor 14. The sequenceofsteps of opera-- tion may be illustrated bythe following table, it being understood that the several movableconanother 24, 25-0, 27, 28-m 1st tap position 24-41, 25--b 27, 28m 1sttransition 7 24--a, 25--b 2'7-m, 28-n 2nd tap position 24, 25-1; 27m,28n 2nd transition 24, 25b 2'7, 28-11 3rd tap position In the firstposition indicated in the table the movable contact members 24 and 25are both in engagement with the contact member a and the movable contactmembers 21 and 28 are both in engagement with the fixed contact member'm connecting the members a and m directly together. In the firsttransition position the C011? tact member 25 moves into engagement withthe fixed contact member b, the other movable contact members remainingunchanged. In the second tap position the contact member 28 has movedinto engagement with the contact member n so that the contact members 24and 25 bridge the contact members a and b and the contact members 21 and28 bridge the contact members m and 11., thus providing an intermediatetap step between a direct connection of the contact members a and m anda direct connection of the contact members I; and n. In the secondtransitional step the contact member 24 has moved into engagement withthe contact member I), the other movable contact members remaining inthe positions as when in the second tap position. In the next or thirdtap position the contact member 21 has moved into engagement with thecontact member 11. so that a direct connection is'provided between thecontact members b and n. Succeeding steps as the movable contact membersmove downwardly over the fixed contact members are performed in a mannersimilar to the steps described above in detail.

In the arrangement illustrated in Fig. 3, the movement or the contactmembers 24, 25, 21 and 28 is similar to that illustrated in Fig. 2, thecontact member 24 being directly connected to the contact member 21 byconductor 29 and the contact member 25 being directly connected to thecontact member 28 by conductor 81, thus elimi- ,nating the preventive.autos 28 shown in Fig. 2

do not wish to belimited otherwiise than by the scope ofthe appendedclaims.

I claim as myinvention:

1. In a regulating transformer, in combination,

a core having three winding legs, a primary winding and a secondarywinding associated with each winding leg, said primary windings beingcon- I neotedin series, two of said windings being provided with tappedconnections, tap changing switches associated therewith, and switchoperating mechanism therefor operative for maintaining the sum of thecoils of these two windings in series at all times substantiallyconstant, the magnetizing effect of these two windings being cumulativewith the winding" on the third leg,

I said three secondary windings being also connected in series, thosesecondary windings on the same two legs with the tapped windings being dfferentially connected.

2. In a regulating transformer, in combination, a core having threewinding legs, a primary winding on each winding leg, the several primaryGil windings being connected in series and each having the same totalnumber of turns, two of said windings being provided with tappedconnections, tap changing switches associated therewith, and switchoperating mechanism therefor for varying the number of turns in seriesand iormaintaining the sum of the number of turns of these two windingsat all times substantially constant, these two windings being soconnected that the magnetizing effects are cumulative with the windingon the third leg, a secondary winding on each winding leg, each of theseveral secondary windings having the same number of turns, and those onthe same two legs with the tapped primary windings being differentiallyconnected.

3. In a regulating transformer, in combination, a core having aplurality of winding legs, a primary winding and a secondary winding oneach of two winding legs, said primary windings being so connected inseries that the magnetizing effects thereof are cumulative, saidwindings being provided with tapped connections and tap changingswitches associated therewith; switch operating mechanism formaintaining the sum of the coils of these two windings in series at alltimes substantially constant, said secondary windings I beingdifferentially connected in series.

4. In a regulating transformer for supplying a variable voltage load, incombination, a core having three winding legs, a primary winding and asecondary winding associated with each winding leg, said primarywindings being connected in series, two of said windings being providedwith tapped connections, tap changing mechanism for maintaining the sumof the coils of these two windings in series at all times substantiallyconstant, the magnetizing eifect of these two windings being cumulativewith the winding on the third leg, said three secondary windings beingalso connected in series with the variable voltage load, those windingson the same two legs with the tapped windings being diil'erentiallyconnected, one terminal of the unregulated primary winding beingconnected to a supply conductor, and a resistor connected between theother terminal and ground,

5. In a regulating transformer for supplying a variable voltage load, incombination, a core having three winding legs, a primary winding and asecondary winding associated with each winding leg, said primarywindings being connected in series, two of said windings being providedwith tapped connections and tap changing switches associated therewith,switch operating mechanisznforrnaintainingthesumof thecoilsofthese twowindings in series at all times substantially constant, the magnetizingeflect of these two windings that are neither connected to the end ofthe ungrounded primary winding or to ground.

6. In a regulating transformer for supplying energy to a variablevoltage load, in combination, a core having three winding legs, a.primary winding and a secondary winding associated with each windingleg, said primary windings being connected in series, two of saidwindings being provided with tapped connections, tap changing mechanismfor maintaining the sum of the coils of these two windings in series atall times substantially constant, the magnetizing effect of these twowindings being cumulative with the winding on the third leg, said threesecondarywindings being also connected in series with the variablevoltage load, those windings on the same two legs with the tappedwindings being diflerentially connected, the unregulated primary windingbeing connected at one end of the series of primary windings and havingone terminal connected to a. supply conductor, a resistor of highresistance connected between the other terminal and ground, and aresistor of high resistance connected between the terminals of theregulated primary windings that are not connected to the end of theungrounded primary winding or to ground.

7. In a transformer for supplying a variable voltage load and a constantvoltage load, in combination, a core having three winding legs, aprimary winding and a secondary winding with each winding leg, saidprimary windings being connected in series, two of said windings beingprovided withtapped connections, tap changing mechanism for maintainingthe sum of the coils of these two windings in series at all timessubstantially constant, the magnetizing effect of these two windingsbeing cumulative with the winding on the third leg, said three secondarywindings being also connectedin series with the variable voltage load,those windings on the same two legs with the tapped windings beingdifferentially connected, and a constant voltage load supplied from thesecondary winding on the leg with the unregulated winding.

FRITZ RAIPAOHIR.

